|Publication number||US7519056 B2|
|Application number||US 10/455,510|
|Publication date||Apr 14, 2009|
|Filing date||Jun 4, 2003|
|Priority date||Jun 4, 2002|
|Also published as||US7548541, US20040017816, US20040078469|
|Publication number||10455510, 455510, US 7519056 B2, US 7519056B2, US-B2-7519056, US7519056 B2, US7519056B2|
|Inventors||Prashanth Ishwar, Ajay Gaonkar, Apurva Mehta, Rajagopalan Subbiah|
|Original Assignee||Alcatel-Lucent Usa Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (23), Non-Patent Citations (2), Referenced by (28), Classifications (22), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is entitled to the benefit of provisional Patent Application Ser. No. 60/385,862, filed 4 Jun. 2002.
The invention relates generally to a technique for managing traffic in a multiport network node, and more particularly, to a technique for managing traffic in a multiport network node that is connected to another network node by a tunnel, for example, a stacked virtual local area network (VLAN) tunnel or a multiprotocol label switching (MPLS) tunnel.
Traditional metropolitan area communications services are based upon technologies such as asynchronous transfer mode (ATM), synchronous optical network (SONET), and Frame Relay technologies, which are optimized for voice communications services. With the increased use of the Internet as a communications medium, non-voice traffic (often referred to as data traffic) is becoming the most prevalent type of network traffic. To meet the increasing demand for data-centric communications services in metropolitan areas, new data-centric metropolitan area networks (MANs) are being built. These new MANs often utilize Ethernet at Layer 2 of the Open System Interconnection (OSI) model to connect nodes within the network (where the OSI model is defined by the International Standardization Organization (ISO)). Ethernet is a popular Layer 2 protocol for use in MANs because of its compatibility with the installed base of end users, its compatibility with the widely used Layer 3 Internet protocol (IP), because of its overall flexibility, and because it is relatively cheap to deploy when compared to other Layer 2technologies.
Although deploying Ethernet as the Layer 2 technology in MANs has many advantages, the end-user customers that are targeted to utilize MANs often desire advanced network services such as quality of service (QoS) guarantees, permanent virtual circuits (PVCs), Virtual Leased Lines (VLLs), and transparent LAN services (TLS). Many of these advanced services can be provided by a network that utilizes a Layer 2technology such as ATM, SONET, or Frame Relay. Ethernet, on the other hand, was not originally designed to provide advanced services and as a result, solutions to customer needs can be more difficult to implement in Ethernet-based networks.
One Ethernet technology that is presently utilized in MANs to provide advanced services to customers is VLAN technology. A VLAN is a group of network devices on different physical LAN segments that communicate with each other as if they were on the same physical LAN segment. The goal of VLAN technology is to make two network devices appear as if they are on the same logical LAN even though they are on different physical LANS.
From the perspective of a particular network switch, a VLAN is a broadcast domain. The broadcast domain can be used for packets, belonging to the VLAN, which are broadcast packets or packets whose destination MAC address has not been learned. A packet that is broadcast within a broadcast domain is sent to all ports in the broadcast domain except the port on which the packet was received. Typically, VLANs are configured within a multiport network node (e.g., a Layer 2 switch) by associating a particular VLAN identifier (ID) with a set of ports. The set of ports defines the broadcast domain of the VLAN within the multiport network node.
In order to provide VLAN services to customers that are connected by intermediate networks, service providers have employed “tunneling” technologies that essentially tunnel VLAN traffic through an intermediate network and deliver the VLAN traffic to a remote-end service provider edge device in the same form as it arrived at the near-end service provider edge device.
While establishing broadcast domains to connect remote customers is fairly straight forward when service provider network nodes are directly connected, the task becomes more difficult when service provider edge devices are connected through an intermediate network using tunneling technologies. In particular, the mere assigning of ports to a VLAN does not ensure that the traffic will be sent in the correct “tunnel” to the desired remote-end service provider edge device. The difficulty of the task is further increased as the number of different customers, service provider nodes, VLANs, and tunnels grows.
In view of the desire for VLAN-based services, what is needed is a technique that enables flexible deployment of VLANs across service provider networks that employ tunneling techniques.
A technique for implementing VLANs across a service provider network involves establishing logical ports that have bindings to transport tunnels. The logical ports are then treated the same as physical ports in defining broadcast domains and forwarding traffic at particular service provider edge devices. Because the logical ports have bindings to transport tunnels, adding a particular logical port to a broadcast domain causes traffic from the respective VLAN to automatically be forwarded in the transport tunnel that is bound to the logical port. Logical ports enable a VLAN that spans an intermediate network to be established simply by adding the respective logical port to the broadcast domain of the VLAN.
Logical ports can be established for the transport of Layer 2 packets using stacked VLAN tunneling and MPLS tunneling. Establishing a logical port that uses stacked VLAN tunneling involves binding a physical port and a stacked VLAN tunnel to the logical port. Traffic that is forwarded to a stacked VLAN logical port is sent out of the service provider edge device from the physical port that is bound to the logical port and in the stacked VLAN tunnel that is bound to the logical port. Establishing a logical port that uses MPLS tunneling involves binding an MPLS tunnel to a logical port. In one embodiment, the logical port is bound to a static MPLS tunnel and in another embodiment, the logical port is bound to a dynamic MPLS tunnel and the destination IP address of the destination service provider edge device. Traffic that is forwarded to an MPLS logical port is sent out of the service provider edge device using the MPLS tunnel that is bound to the logical port.
Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
Throughout the description, similar reference numbers may be used to identify similar elements.
Using conventional VLAN techniques, the broadcast domain for VLAN 100 at SPED A can be configured by adding physical ports P1 and P3 to the broadcast domain. Traffic arriving at SPED A on VLAN 100 is forwarded to at least one of the ports in the broadcast domain (except the port on which the traffic arrived) depending on whether the traffic is broadcast traffic, traffic for which the destination MAC address has not yet been learned, or learned traffic. A problem with this approach is that simply forwarding VLAN 100 traffic to physical port P3 does not ensure that the VLAN 100 traffic will be sent out in the target stacked VLAN tunnel (e.g., stacked VLAN tunnel 600). In order for the VLAN 100 traffic to be sent out on the target stacked VLAN tunnel, there must be some relationship configured between VLAN 100, physical port P3, and the target stacked VLAN tunnel.
In accordance with an embodiment of the invention, a logical port is created at SPED A that includes a binding to a physical port and to a target stacked VLAN tunnel. The logical port can then be used in defining the broadcast domain of a VLAN and forwarding traffic. In the embodiment of
In an embodiment, the process of binding a physical port and a stacked VLAN tunnel to a logical port involves allocating a table entry in an exit port table for the logical port. The table entry maps the logical port to the physical port of exit and to the VLAN ID of the outer IEEE 802.1Q header.
In an example operation, a packet is received from customer C1 at port P1 of SPED A 402. The received packet is identified as belonging to VLAN 100 and the broadcast domain for VLAN 100 is identified. As depicted in
Multiple stacked VLAN tunnels often emanate from the same port of a SPED in order to connect the SPED to multiple other SPEDs through an intermediate network.
Another technique that is used to tunnel traffic through an intermediate network involves the use of multiprotocol label switching (MPLS). Using MPLS, incoming packets are assigned a “label” by a “label edge router.” Packets are forwarded along a “label switch path” (LSP) through a series of connected “label switch routers.” Each label switch router makes forwarding decisions based on the contents of the label. At each hop, the label switch routers strip off the existing label and apply a new label that tells the next hop how to forward the packet. LSPs are provisioned using Resource Reservation protocol (RSVP) and Label Distribution protocol (LDP). LSPs can be established by network operators for a variety of purposes, such as to guarantee a certain level of performance, to route around network congestion, or to create tunnels for virtual private networks. MPLS can be used to create end-to-end circuits, with specific performance characteristics, across any type of transport medium.
In an embodiment of MPLS tunneling, a customer's traffic (e.g., an Ethernet packet) is switched or routed to a SPED, which serves the function of an MPLS label edge router. The SPED determines the VLAN to which the packet belongs, either by looking at the 802.1Q header or by determining the VLAN associated with the incoming port. The Ethernet packet is then mapped to a user-defined Forwarding Equivalence Class (FEC), which defines how the packet gets forwarded. An FEC lookup yields the outgoing physical port and two MPLS labels. The first MPLS label is placed at the top of the label stack and is referred to as the “tunnel label.” The tunnel label is used to carry the frame across the intermediate network. The second label is placed at the bottom of the label stack and is referred to as the “VC label.” The VC label is used by the egress label edge router (i.e., the SPED at which the packet exits the MPLS domain) to determine how to process the packet. After adding two MPLS headers (one for each MPLS label), the packet is encapsulated into the format that corresponds to the outgoing interface.
As with the stacked VLAN embodiment, using conventional VLAN techniques, a broadcast domain for VLAN 100 at SPED A can be configured by adding physical ports P1 and P3 to the broadcast domain. Traffic arriving at SPED A on VLAN 100 is forwarded to at least one of the ports in the broadcast domain (except the port on which the traffic arrived) depending on whether the traffic is broadcast traffic, traffic for which the destination MAC address has not yet been learned, or learned traffic. A problem with this approach is that simply forwarding VLAN 100 traffic to physical port P3 does not ensure that the VLAN 100 traffic will be sent out in the target MPLS tunnel (e.g., using LSP 650). In order for the VLAN 100 traffic to be sent out on the target MPLS tunnel, there must be some relationship configured between VLAN 100 and the target MPLS tunnel.
In accordance with an embodiment of the invention, a logical port is created which includes a binding to the target MPLS tunnel. The logical port can then be used in defining the broadcast domain of a VLAN. In the example of
In an example operation, a packet is received from customer C1 at port P1 of SPED A 902. The received packet is identified as belonging to VLAN 100 and the broadcast domain for VLAN 100 is identified. As depicted in
MPLS tunneling can also be implemented using dynamic MPLS tunnels. Dynamic MPLS tunnels are MPLS tunnels that do not specify a particular LSP that must be used to reach the target destination. Using a dynamic MPLS tunnel, the particular LSP that is utilized may change from time to time in response to factors such as traffic load and latency.
In accordance with an embodiment of the invention, a logical port is created which includes a binding to the target MPLS tunnel and to the target destination. The logical port can then be used in defining the broadcast domain of a VLAN. In the example of
In an example operation, a packet is received from customer C1 at port P1 of SPED A 1102. The received packet is identified as belonging to VLAN 100 and the broadcast domain for VLAN 100 is identified. As depicted in
Although the stacked VLAN and MPLS domains are depicted as separate networks, the stacked VLAN and MPLS domains may be implemented totally, or partially, on common network devices.
Although stacked VLAN tunnels and MPLS tunnels have been described, other transport tunnels could be bound to a logical port. Additionally, although the VLAN process is described in a single direction, the same processes could be implemented at the far-end SPEDs to achieve bidirectional functionality.
Each of the line cards includes at least one port 1516, a processor 1518, and memory 1520, which perform functions such as receiving traffic into the network node, buffering traffic, making forwarding decisions, and transmitting traffic from the network node. The processor within each line card may include a multifunction processor and/or an application specific processor that is operationally connected to the memory. The processor performs functions such as packet parsing, packet classification, and making forwarding decisions. The memory within each line card may include circuits for storing operational code, for buffering traffic, for storing logical port information, and for storing other data structures. Operational code is typically stored in non-volatile memory such as electrically erasable programmable read-only memory (EEPROM) or flash ROM while traffic and data structures are typically stored in volatile memory such as random access memory (RAM). Example data structures that are stored in the RAM include traffic forwarding information (i.e., exit port tables). Forwarding information may also be stored in content addressable memory (CAM) or a combination of CAM and RAM. Although the processor and memory are depicted as separate functional units, in some instances, the processor and memory are integrated onto the same device. In addition, there may be more than one discrete processor unit and more than one memory unit on the line cards.
The switch fabric 1504 provides datapaths between input ports and output ports and may include, for example, shared memory, shared bus, and crosspoint matrices. Although not depicted, the network node 1500 may be equipped with redundant switch fabrics.
The primary and secondary control modules 1506 and 1508 support various functions, such as network management functions and protocol implementation functions. Example network management functions that are performed by the control modules include implementing configuration commands, providing timing control, programming hardware tables, providing system information, supporting a user interface, managing hardware changes, bus management, managing logical ports, managing VLANs, and protocol processing. Example protocols that are implemented by the control modules include Layer 2 (L2) protocols, such as L2 Learning, STP, and LACP and Layer 3 (L3) protocols such as OSPF, BGP, and ISIS. The layers are defined by the ISO in the OSI model.
Each of the control modules 1506 and 1508 includes a processor 1522 and memory 1524 for carrying out the designated functions. The processor within each control module may include a multifunction microprocessor and/or an application specific processor that is operationally connected to the memory. The memory may include EEPROM or flash ROM for storing operational code and DRAM for buffering traffic and storing data structures, such as logical port information and VLAN tables. Although the processor and memory are depicted as separate functional units, in some instances, the processor and memory are integrated onto the same device. In addition, there may be more than one discrete processor unit and more than one memory unit on the control modules. Throughout the description, similar reference numbers may be used to identify similar elements.
In an embodiment, the logical port functionality that is described above with reference to
Although some of the broadcast domains are described as including only two ports (physical and or logical ports), it should be understood that the broadcast domains could include more than two ports.
Although specific embodiments of the invention have been described and illustrated, the invention is not to be limited to the specific forms or arrangements of parts as described and illustrated herein. The invention is limited only by the claims.
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|U.S. Classification||370/389, 709/227, 370/395.53, 370/228, 370/235, 709/243, 370/401, 370/386, 709/203|
|International Classification||G06F15/173, H04L12/56, H04L12/28, G06F15/16, H04L12/24, H04L12/46|
|Cooperative Classification||H04L41/00, H04L45/50, H04L12/467|
|European Classification||H04L12/46V2, H04L41/00, H04L45/50, H04L12/24|
|Sep 8, 2003||AS||Assignment|
Owner name: RIVERSTONE NETWORKS, INC., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ISWAR, PRASHANTH;GOANKAR, AJAY;MEHTA, APURVA;AND OTHERS;REEL/FRAME:014463/0467
Effective date: 20030815
|Feb 9, 2009||AS||Assignment|
Owner name: LUCENT TECHNOLOGIES INC., NEW JERSEY
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:RIVERSTONE NETWORKS, INC.;REEL/FRAME:022224/0023
Effective date: 20060427
Owner name: ALCATEL-LUCENT USA INC., NEW JERSEY
Free format text: MERGER;ASSIGNOR:LUCENT TECHNOLOGIES INC.;REEL/FRAME:022224/0290
Effective date: 20081101
|Sep 27, 2012||FPAY||Fee payment|
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